rename letsencrypt-2 image folder to acme-nginx and add jenkins file for building image

dockerfiles/tasks/acme-nginx/build.Jenkinsfile

@@ -0,0 +1,17 @@
+pipeline {
+    agent { label 'docker' }
+    triggers {
+        cron('@daily')
+    }
+    options {
+        disableConcurrentBuilds()
+        buildDiscarder(logRotator(numToKeepStr: '2'))
+    }
+    stages {
+        stage('Build Image') {
+            steps {
+                build job: '_build_image', parameters: [string(name: 'IMAGE', value: 'acme-nginx')], quietPeriod: 1
+            }
+        }
+    }
+}